class Container {
  static of(value) {
    return new Container(value)
  }

  constructor(value) {
    this._value = value
  }

  map(fn) {
    return Container.of(fn(this._value))
  }
}

class MayBe {
  static of(val) {
    return new MayBe(val)
  }

  constructor(value) {
    this._value = value
  }

  isNothing() {
    return this._value === null || this._value === undefined
  }

  map(fn) {
    return this.isNothing() ? this :
      MayBe.of(fn(this._value))
  }
}

module.exports = { Container, MayBe }